Self-aligned punch through stopper liner for bulk FinFET

ABSTRACT

A technique relates to forming a self-aligning field effect transistor. A starting punch through stopper comprising a substrate having a plurality of fins patterned thereon, an n-type field effect transistor (NFET) region, a p-type field effect transistor (PFET) region, and a center region having a boundary defect at the interface of the NFET region and the PFET region is first provided. The field effect transistor is then masked to mask the NFET region and the PFET region such that the center region is exposed. A center boundary region is then formed by etching the center region to remove the boundary defect.

BACKGROUND

The present invention relates to metal-oxide-semiconductor field-effecttransistors (MOSFET), and more specifically, to fin-type field-effecttransistors (FinFET).

The MOSFET is a transistor used for amplifying or switching electronicsignals. The MOSFET has a source, a drain, and a metal oxide gateelectrode. The metal gate is electrically insulated from the mainsemiconductor n-channel or p-channel by a thin layer of insulatingmaterial, for example, silicon dioxide or glass, which makes the inputresistance of the MOSFET relatively high. The gate voltage controlswhether the path from drain to source is an open circuit (“off”) or aresistive path (“on”).

N-type field effect transistors (NFET) and p-type field effecttransistors (PFET) are two types of complementary MOSFETs. The NFET useselectrons as the current carriers and is built with n-doped source anddrain junctions. The PFET uses holes as the current carriers and isbuilt with p-doped source and drain junctions.

The fin-type field effect transistor (FinFET) is a type of MOSFET. TheFinFET contains a conformal gate around the fin that mitigates theeffects of short channels and reduces drain-induced barrier lowering.The “fin” refers to the narrow channel between source and drain regions.Often, a thin insulating high-k gate oxide layer around the finseparates the fin channel from the gate metal.

SUMMARY

According to an embodiment of the present invention, a method of makinga self-aligned field effect transistor structure is provided. The methodincludes providing a starting punch through stopper comprising asubstrate having a plurality of fins patterned thereon, an n-type fieldeffect transistor (NFET) region, a p-type field effect transistor (PFET)region, and a center region having a boundary defect at the interface ofthe NFET region and the PFET region. In some aspects, the method furtherincludes masking the NFET region and the PFET region such that thecenter region is exposed and etching the center boundary region toremove the boundary defect.

According to one embodiment, a method of making a self-aligned fieldeffect transistor structure is provided. The method includes providing astarting punch through stopper comprising a substrate having a pluralityof fins patterned thereon, an n-type field effect transistor (NFET)region having a boron doped layer deposited over at least one of theplurality of fins, a p-type field effect transistor (PFET) region havinga phosphorous or arsenic doped layer deposited over at least one of theplurality of fins, and a center region having a boundary defect at theinterface of the NFET region having the boron doped layer depositedthereon and the PFET region having the phosphorous or arsenic dopedlayer deposited thereon. The method further includes masking the NFETregion having the boron doped layer deposited thereon and the PFETregion having a phosphorous doped layer deposited thereon such that thecenter region is exposed and etching the center boundary region toremove the boundary defect. Additionally, the method includes removingthe mask covering the NFET region having the boron doped layer depositedthereon and the PFET region having a phosphorous doped layer, fillingthe etched center boundary region with an insulator material, andplanarizing the punch through stopper having the center boundary regionfilled with the insulator material. Further, the method includesrevealing a portion of the plurality of fins patterned in the substratesuch that at least a portion of the boron doped layer adjacent to thefins forming the NFET region and at least a portion of the phosphorousor arsenic doped layer adjacent to the fins forming the PFET region isrevealed and doping a portion of the fins and substrate that is adjacentto the boron doped layer with boron type dopants and doping a portion ofthe fins and substrate that are adjacent to the phosphorous or arsenicdoped layer with phosphorous or arsenic type dopants.

According to one embodiment, a self-aligned field effect transistorstructure is provided. The self-aligned field effect transistorstructure includes a bulk substrate having a plurality of fins patternedtherein. The self-aligned field effect transistor structure alsoincludes an n-type field effect transistor region formed of at least oneof the plurality of fins patterned on the substrate, the n-type fieldeffect transistor region having a boron doped layer formed therein, anda p-type field effect transistor region formed of at least one of theplurality of fins patterned on the substrate, the p-type field effecttransistor region having a phosphorous or arsenic doped layer formedtherein. Furthermore, the self-aligned field effect transistor structureincludes a boundary region between the n-type filed effect transistorregion and the p-type field effect transistor region comprising aninsulator material disposed between the n-type filed effect transistorregion and the p-type field effect transistor region such that there isa separation between the boron doped layer of the n-type filed effecttransistor region and the phosphorous or arsenic doped layer of thep-type field effect transistor region.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The forgoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a cross-sectional side view of an example starting FET with afin structure and punch through stopper (PTS) having a boundary defect;

FIG. 2 is an example conventional method of forming the FET of FIG. 1;

FIGS. 3-7 illustrate an example boundary cut process used to selectivelycut a boundary portion of a PTS and any defect that exists therein,wherein:

FIG. 3 is a cross-section view of the starting PTS having fin cut masksformed thereon to create a cut region;

FIG. 4A is a cross-sectional view of the PTS having the center regioncut such that the cut stops at an upper surface of the substrate 102;

FIG. 4B is a cross-sectional view of the PTS having the center regioncut such that the cut stops at a surface that is just below an uppersurface of the substrate;

FIG. 5 is a cross-sectional view of a planarized PTS having the centerregion filled with an STI oxide;

FIG. 6 is a cross-sectional view of the PTS having a portion of the finsrevealed such that a portion of the BSG layer and PSG layer is exposed;

FIG. 7 is a cross-sectional view of the PTS having doped portions of thefins and substrate that are adjacent to the BSG layer and PSG layer; and

FIG. 8 is a cross-section view of an example gate formed on a fin of thePTS.

DETAILED DESCRIPTION

As stated above, the present invention relates to MOSFETs, andparticularly to interconnect technology, which are now described indetail with accompanying figures. It is noted that like referencenumerals refer to like elements across different embodiments.

The following definitions and abbreviations are to be used for theinterpretation of the claims and the specification. As used herein, theterms “comprises,” “comprising,” “includes,” “including,” “has,”“having,” “contains” or “containing,” or any other variation thereof,are intended to cover a non-exclusive inclusion. For example, acomposition, a mixture, process, method, article, or apparatus thatcomprises a list of elements is not necessarily limited to only thoseelements but can include other elements not expressly listed or inherentto such composition, mixture, process, method, article, or apparatus.

As used herein, the articles “a” and “an” preceding an element orcomponent are intended to be nonrestrictive regarding the number ofinstances (i.e. occurrences) of the element or component. Therefore, “a”or “an” should be read to include one or at least one, and the singularword form of the element or component also includes the plural unlessthe number is obviously meant to be singular.

As used herein, the terms “invention” or “present invention” arenon-limiting terms and not intended to refer to any single aspect of theparticular invention but encompass all possible aspects as described inthe specification and the claims.

As used herein, the term “about” modifying the quantity of aningredient, component, or reactant of the invention employed refers tovariation in the numerical quantity that can occur, for example, throughtypical measuring and liquid handling procedures used for makingconcentrates or solutions. Furthermore, variation can occur frominadvertent error in measuring procedures, differences in themanufacture, source, or purity of the ingredients employed to make thecompositions or carry out the methods, and the like. In one aspect, theterm “about” means within 10% of the reported numerical value. Inanother aspect, the term “about” means within 5% of the reportednumerical value. Yet, in another aspect, the term “about” means within10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% of the reported numerical value.

Punch through stopper (PTS) formation is a process to form doped regionsbelow active fins to prevent source/drain (S/D) leakage. Traditionalmethods of forming the PTS uses boron (B) doped silicate glass layers(BSG) and phosphorous (P) doped silicate glass (PSG) layers. Besides BSGand PSG, any other suitable material containing boron or phosphorus canalso be used as dopant sources. Furthermore, arsenic doped material canbe used in lieu of PSG as n-type dopant source. In some aspects, BSGlayers can be utilized with NFET, and PSG layers are utilized with PFET.It is through film patterning processes that BSG layers for NFET and PSGlayers for PFET are made. This process, however, requires strict controlof process alignment, such as over block layers and often may leave astringer-type defect at the boundary between the NFET and PFET. Thus, asis discussed below, it may be desirable to remove these boundarydefects.

FIG. 1 is a cross-sectional side view of an example starting FET with afin structure and punch through stopper (PTS) having the above discussedboundary defect. As used herein, “punch through stopper (PTS)” refers toa portion of a fin that is doped under the fin channel. As shown, astarting FET structure 100 is a starting PTS structure that includes aplurality of fins 104, 106 patterned in a bulk substrate 102. A firstgroup of fins 104 defines an NFET region of the FET 100 while a secondgroup of fins 106 forms a PFET region of the FET 100. In some aspects,the fins 104 b, 106 b that are immediately adjacent the center regioncontaining a defect 118, as is discussed in more detail below withrespect to FIG. 3, can be dummy fins. That is, these fins 104 b, 106 bimmediately adjacent a defect 118 can be non-active device fins to beremoved later.

Moreover, as will be discussed in more detail below, the fins 104 caninclude a hardmask layer 105 formed above the substrate fin-formingmaterial. Similarly, the fins 106 can include a hardmask layer 105 andadditionally can include a second substrate layer 107 that is formed ofa different material than substrate 102. For example, the secondsubstrate layer 107 can be formed of a silicon germanium (SiGe)material. Immediately above the substrate 102 in the NFET region is aboron (B) doped layer (BSG) 108. Similarly, directly above the substrate102 on the PFET side is a phosphorous (P) doped (PSG) layer 110. Abovethe BSG layer 108 and PSG layer 110 are hardmask layers 112, 114. Insome aspects, the hardmask layers are formed of silicon nitride (SiN).Furthermore, the starting FET 100 includes an insulator layer 116, suchas a Shallow Trench Isolation (STI) oxide layer or any suitableinsulator material that sits above the respective hardmask layers 112,114.

This starting FET 100, as is shown in FIG. 1, contains a boundary defect118 that occurs at the boundary between the NFET and PFET. Specifically,the defect 118 can include stringers formed in the PSG layer 110 andhardmask layer 114 at the point where the PSG layer 110 and hardmasklayer 114 meets the BSG layer 108 and its hardmask layer 112. Thisdefect 118 is a result of the variations of deposition and patterningprocess used to form the starting FET 100 shown in FIG. 1. Since thedefect 118 contains both BSG and PSG, both boron and phosphorus (orarsenic as described herein) simultaneously diffuse towards adjacentregions, leading to undesired variation of dopant concentration and thusvariation of device characteristics. This process is detailed in FIG. 2.

FIG. 2 illustrates a block diagram of an exemplary PTS forming process200 that creates the starting FET 100 shown in FIG. 1. As shown, the PTSforming process 200 includes a first step 202 of forming a plurality offins on a substrate. The substrate formed in this first step 202, suchas substrate 102 shown and described in FIG. 1, can be formed of anysuitable substrate material. In some aspects the substrate is bulksilicon substrate. Non-limiting examples of suitable substrate materialsinclude silicon, silicon dioxide, aluminum oxide, sapphire, germanium,gallium arsenide (GaAs), an alloy of silicon and germanium, indiumphosphide (InP), or any combination thereof. The thickness of thesubstrate is not intended to be limited.

As will be appreciated by those of ordinary skill in the art, theplurality of fins can be formed on the substrate using a variety ofsuitable techniques. For example, fins can be formed in the substrateusing a time-based anisotropic etching process that utilizes a hardmasklayer and resist patterns to protect the fin-forming substrate fromremoval during the etching process. Alternatively, fins can be formed bysidewall imaging transfer (SIT) technique. In some aspects, for example,the fins—such as fins 104, 106—can have height of about 50 nanometers to150 nanometers and a thickness of about 5 nanometers to about 15nanometers, although any desired height and thickness can be achieved.

In some embodiments, the fin forming step 202 can include a step thatproduces a second substrate material in at least some of the fins. Forexample, a silicon germanium layer 107 can be formed, such as byepitaxial growth, on a PFET group of fins, as is shown in FIG. 1. Aswill be appreciated by one of ordinary skill in the art, a silicongermanium layer can be formed by deposition with a chemical vapordeposition process or growth with a surface reaction epitaxy process. Insome embodiments, fins 104, 106 contain similar materials, such assilicon. In other embodiment, fins 104, 106 contain different materials,for example, silicon fins for NFET and silicon germanium fins for PFET.

Further, the step 204 includes depositing a BSG layer on the substrateand plurality of fins. Specifically, a chemical vapor deposition (CVD)or atomic layer deposition (ALD) process can be used to form the BSGlayer across the substrate and fins. After the BSG layer is deposited, ahardmask layer, such as SiN, can be formed above the BSG layer, whichnow covers both the NFET and PFET fins. The insulating hardmask layercan be any suitable hardmask, for example, silicon nitride (SiN), SiOCN,or SiBCN. It will be appreciated that layers other than boron dopedlayers can be utilized. For example indium doped oxide, indium dopedsilicate glass layers can be used. The BSG layer thickness ranges from 1nanometer (nm) to 10 nanometers (nm), although thicker or thinner BSGlayers are also conceived. The hardmask layer thickness ranges from 1nanometer (nm) to 10 nanometer (nm), although thicker or thinner BSGlayers are also conceived.

The process 200 can next include the step 206 of forming a block maskover the NFET portion of the PTS in order to preserve the BSG layer fromfuture etching. With the BSG layer masked as desired, the process 200can include the step 208 of selectively etching to the substrate. Inthis step 208, the BSG layer is removed from the PFET side of thesubstrate and fins.

Next, in step 210, a PSG layer can be deposited over the PFET portion ofthe FET. Just as with the BSG deposition, the PSG deposition process caninclude either chemical vapor deposition (CVD) or atomic layerdeposition (ALD). It will be appreciated that layers other thanphosphorous doped layers can be utilized. For example phosphorus dopedoxide, arsenic doped oxide, and arsenic doped silicate glass dopedlayers can be used. This step 210 can also include deposition of ahardmask, such as SiN, layer. It is at this point in the process 200that boundary defects between the PFET and NFET portions are producedduring the deposition of the PSG and SiN mask layers adjacent to the BSGlayer and its corresponding SiN mask layer, such as is shown by defectregion 118 in FIG. 1. The PSG layer thickness ranges from 1 nanometer(nm) to 10 nanometers (nm), although thicker or thinner PSG layers arealso conceived.

Next, any mask layers that may be present over the PTS at this point canbe removed in step 212, which includes selectively etching to thehardmask layers that were deposited above the BSP and PSG layers.Lastly, to form the starting FET 100 of FIG. 1, a layer of STI oxide canbe formed over the body of the PTS and planarized to the top of the finsusing a chemical mechanical polishing (CMP) process. As such, a startingPTS is formed that has the above described boundary defect that now mustbe removed.

FIGS. 3-7 illustrate an example boundary cut process used to selectivelycut, or remove, the boundary portion of the PTS and any defect thatexists therein.

FIG. 3 is a cross-section view of the starting PTS having fin cut masksformed thereon to create a cut region. As shown in FIG. 3, the startingFET 100 is prepared to have a center, boundary region 120 removed, whilemaintaining the peripheral fins 104, 106 intact to form source/drain(S/D) active regions later in the process. Specifically, the center,boundary region 120 can include at least one boundary fin 104 b and atleast one boundary fin 106 b. As shown in FIG. 3, in order to protectthe peripheral fins 104, 106 from the boundary cut process, theperipheral fins 104, 106 are covered with a fin cut mask 122. The fincut masks 122 can be formed by suitable masking techniques, such asphotolithographic deposition and patterning.

FIG. 4A is a cross-sectional view of the FET 100 having the centerregion 120 cut such that the etch stops at an upper surface 124A of thesubstrate 102. FIG. 4B is a cross-sectional view of the FET 100 havingthe center region 120 cut such that the etch stops at a surface 124Bthat is just below an upper surface 124A of the substrate 102. Aftermasking the peripheral NFET and PFET regions as shown in FIG. 3, thecenter, boundary region 120 is cut to remove the boundary fins 104 b,106 b (sometimes referred to as dummy fins), the surrounding oxide layer116 that is in the unmasked center region 120, as well as the boundarydefect 118. The cut can be performed with any suitable method, such asan etching process. For example, either chemically selective isotropicor anisotropic etches or timed isotropic or anisotropic etches can beutilized. For example, in some aspects a reactive ion etch (RIE) processis used. In some aspects, however, fins 104 b, 106 b are cut and inthese aspects, a timed etch can be used. As shown in FIG. 4A, thiscutting process can be performed such that the etch stops at the uppermost surface 124A of the substrate 102. In some aspects, the cuttingprocess can be performed such that the etch stops at a surface 124B thatis just below the upper most surface 124A of the substrate 102. Thus, inthe illustrated embodiment of FIG. 4B, the etching process removes aportion of the exposed substrate 102.

FIG. 5 is a cross-sectional view of a planarized FET 100 having thecenter region 120 filled with an STI oxide. Once the center region 122containing any boundary defect 118 is removed, i.e., cut, the fin cutmasks 118 can be removed and the center region 122 can be filled with aninsulator 116, such as a Shallow Trench Isolation (STI) oxide, usingsuitable techniques. For example, the entire punch through structure canbe filled with the insulator, thus filling in the center region 118.Once the center region is filled, the FET 100 can be planarized using achemical mechanical polish (CMP) procedure. In some aspects, theplanarization can be terminated at the upper-most hardmask layer 126disposed on the fins.

FIG. 6 is a cross-sectional view of the FET 100 having a portion of thefins 104, 106 revealed such that a portion of the BSG layer 108 and PSGlayer 110 is exposed. By exposing portions of the fins 104, 106 asshown, the fins are prepared for gate formation steps as will bediscussed below. Moreover, by revealing the fins in such a manner as toadditionally reveal the BSG layer 108 and PSG layers 110, the portionsof the fins 104, 106 and substrate 102 that are adjacent to the BSG 108and PSG 110 layers can be doped in an annealing step. To reveal thefins, suitable etching techniques, including anisotropic and isotropicetching, can be utilized to remove a specified depth of STI oxide 116 aswell as portions of the BSG layer 108, PSG layer 110, and hardmasklayers 105, 112, 114 that are adjacent to the fins 104, 106. As is shownin FIG. 6, the fin-reveal etch can be selective for the silicon and/orsilicon germanium substrate materials 107 such that only the finstructure remains intact. In some aspects, the fm-reveal etch can be atimed etch.

FIG. 7 is a cross-sectional view of the FET 100 having doped portions128, 130 of the fins and substrate that are adjacent to the BSG layer108 and PSG layer 110. Following the fin reveal, it may be beneficial todope portions of the fins 104, 106 and/or substrate 102 with boron (B)and/or phosphorous (P) type dopants. Specifically, the fins andsubstrate adjacent to the BSG layer of the NFET region 128 can, in someaspects, be doped with a B type dopant. Similarly, the fins andsubstrate adjacent to the PSG layer of the PFET region 130 can be dopedwith a P type dopant. In some aspects, the doping process can include anannealing step to aid in diffusion of the dopant into the adjacent PTSregions 128, 130. As such PTS regions 128, 130—i.e., a portion of thefins 104, 106 are doped under the respective fin channels—are formed. Insuch an annealing step, the FET 100 can be, for example, heated andslowly cooled.

Finally, following doping and annealing of the adjacent regions 128,130, the FET structure 100 can have at least one gate formed thereon.FIG. 8 is a cross-section view of an example gate stack 180 formed on afin 104 of the FET 100. The gate stack 180 can be formed of any suitablegate forming method. As such, the gate stack 180 can include a high-kdielectric layer 182 and a gate metal region 184.

Any suitable gate formation techniques may be employed. For example, inone aspect a gate first process is utilized. In such a gate firstprocess, a gate dielectric layer—such as a high-k layer—can be depositedalong the surface of the FET 100, including over the revealed fins andSTI oxide layer. Gate metal can then be deposited on the high-k layer toform the gate regions. After the gate metal is deposited, aphotolithographic patterning and etching process such as, for example,reactive ion etching (RIE) is performed to pattern the gate stack 180.Subsequently, a spacer 186 is formed by, for example, depositing a layerof nitride or oxide material and performing an anisotropic etchingprocess to define the spacer 186 along sidewalls of the gate stack 180.Following the formation of the spacers 186 active regions may be formedfrom the fins 104, 106 by a suitable process. In one embodiment, anepitaxial growth process may be performed that grows a semiconductormaterial from exposed portions of the fins 104, 106. Following theepitaxial growth process, ion implantation and annealing may beperformed to diffuse dopants into the fins 104,106. In otherembodiments, the dopants may be added in-situ during the epitaxialgrowth process.

In an alternative exemplary embodiment, the FET devices may be formedusing a gate last process. In such a process, following the formation ofthe fins and the FET 100, a layer of dummy gate material, such as, forexample, a polysilicion material and a layer of hard mask material isdeposited over the fins 104, 106. A photolithographic masking andetching process such as, for example, RIE is performed to pattern dummygate stacks. Following the formation of the dummy gate stacks, a spacermaterial layer is deposited and etched to form spacers 186 adjacent tothe sidewalls of the dummy gate stack. The fins 104, 106 may be doped toform active regions by any suitable process such as, for example, an ionimplantation and annealing process, or an epitaxial growth process.After the active regions are formed, an insulator layer, such as, forexample, an oxide layer may be disposed and planarized to expose thedummy gate stacks. The dummy gate stacks are removed, and replaced withreplacement metal gate 184 materials.

Following the formation of the gates, conductive contacts may be formedby, for example, etching vias in the insulator layer to expose theactive regions of the devices, and depositing conductive material in thevias (not shown).

It will further be appreciated by one of ordinary skill in the art thatthe fins can also be modified, i.e., widened, using epitaxial growtheither before, during, or after gate formation. As used herein,deposition is any process that grows, coats, or otherwise transfers amaterial onto the wafer. Available technologies include, but are notlimited to, thermal oxidation, physical vapor deposition (PVD), chemicalvapor deposition (CVD), electrochemical deposition (ECD), molecular beamepitaxy (MBE) and more recently, atomic layer deposition (ALD) amongothers.

As used herein, removal is any process that removes material from thewafer: examples include etch processes (either wet or dry), andchemical-mechanical planarization (CMP), etc.

As used herein, patterning is the shaping or altering of depositedmaterials, and is generally referred to as lithography. For example, inconventional lithography, the wafer is coated with a chemical called aphotoresist; then, a machine called a stepper focuses, aligns, and movesa mask, exposing select portions of the wafer below to short wavelengthlight; the exposed regions are washed away by a developer solution.After etching or other processing, the remaining photoresist is removed.Patterning also includes electron-beam lithography, nanoimprintlithography, and reactive ion etching.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, element components,and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiment was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

The flow diagrams depicted herein are just one example. There may bemany variations to this diagram or the steps (or operations) describedtherein without departing from the spirit of the invention. Forinstance, the steps may be performed in a differing order or steps maybe added, deleted or modified. All of these variations are considered apart of the claimed invention.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A self-aligned field effect transistor structure,comprising: a bulk substrate having a plurality of fins patternedtherein; an n-type field effect transistor region formed of at least oneof the plurality of fins patterned on the substrate, the n-type fieldeffect transistor region having a boron doped layer formed on a portionof the fin and a first hardmask layer formed on the boron doped layer ofthe n-type field effect transistor region; a p-type field effecttransistor region formed of at least one of the plurality of finspatterned on the substrate, the p-type field effect transistor regionhaving a phosphorous or arsenic doped layer formed on a portion of thefin and a second hardmask layer formed on the phosphorous or arsenicdoped layer of the p-type field effect transistor region, wherein thephosphorous or arsenic doped layer is in direct contact with the portionof the fin; a boundary region between the n-type field effect transistorregion and the p-type field effect transistor region comprising aninsulator material disposed between the n-type field effect transistorregion and the p-type field effect transistor region such that there isa separation between the boron doped layer of the n-type field effecttransistor region and the phosphorous or arsenic doped layer of thep-type field effect transistor region; wherein the boron doped layer andthe phosphorous or arsenic doped layer do not physically contact eachother; wherein the insulator material is disposed between the firsthardmask layer and the second hardmask layer; wherein the insulatormaterial does not physically contact the plurality of fins; and whereinthe insulator material is in physical contact with the bulk substrate inthe boundary region.
 2. The self-aligned field effect transistorstructure of claim 1, wherein the at least one of the plurality of finsforming the p-type field effect transistor region comprises a silicongermanium material.
 3. The self-aligned field effect transistorstructure of claim 1, wherein an unrevealed portion of the at least oneof the plurality of fins forming the p-type field effect transistorregion is doped with a phosphorous type dopant.
 4. The self-alignedfield effect transistor structure of claim 1, wherein an unrevealedportion of the at least one of the plurality of fins forming the n-typefield effect transistor region is doped with a boron type dopant.
 5. Theself-aligned field effect transistor structure of claim 1, furthercomprising at least one gate.
 6. The self-aligned field effecttransistor structure of claim 1, wherein the boron doped layer of then-type field effect transistor region is conformally deposited on top ofthe plurality of fins.
 7. The self-aligned field effect transistorstructure of claim 6, wherein the boron doped layer of the n-type fieldeffect transistor region is a layer that is deposited by chemical vapordeposition or atomic layer deposition.
 8. The self-aligned field effecttransistor structure of claim 1, wherein the phosphorous or arsenicdoped layer of the p-type field effect transistor region is conformallydeposited on top of the plurality of fins.
 9. The self-aligned fieldeffect transistor structure of claim 8, wherein the phosphorous orarsenic doped layer of the p-type field effect transistor region is alayer that is deposited by chemical vapor deposition or atomic layerdeposition.
 10. The self-aligned field effect transistor structure ofclaim 1, wherein the boron doped layer of the n-type field effecttransistor region has a thickness of 1 nm to 10 nm.
 11. The self-alignedfield effect transistor structure of claim 1, wherein the phosphorous orarsenic doped layer has a thickness of 1 nm to 10 nm.
 12. Theself-aligned field effect transistor structure of claim 1, wherein theinsulator material comprises a shallow trench isolation oxide.
 13. Theself-aligned field effect transistor structure of claim 1, wherein atleast one of the plurality of fins is doped under a fin channel.
 14. Theself-aligned field effect transistor of claim 5, wherein the gatecomprises a high-k dielectric layer.
 15. The self-aligned field effecttransistor of claim 5, wherein the gate comprises a gate metal region.